1. Field of the Invention
The present invention relates a pneumatic tire and more particularly to a pneumatic tire which allows the estimation of an internal failure of the tire only from the observation of the external appearance of the tire.
2. Description of the Related Art
For example, when a pneumatic tire goes flat and run-flat driving continues with zero inflation pressure, the tire is subject to a large local load, so that temperature of the surface and inside of the tire increases, and this may cause troubles such as thermal deterioration of carcass cords and belt edge separation. However, it is very difficult for a mechanic or the like to detect during repairing a flat tire whether or not there is an internal failure only by observing the external appearance of the flat tire.
Pamphlet of WO 2004/014671 proposes a method for estimating a failure of a run-flat tire using a detection unit. In this method, the detection unit is disposed in the tire to measure ambient temperature in the cavity of the tire, so that an abnormal temperature increase is detect. However, this method has a problem that a signal converter, a transmitter, a receiver, and the like must be provided in addition to the temperature sensor and not only cost but also weight increases.